"The knife, unfortunately, hit his heart. His condition has stabilised, but I cannot say that there's no threat to his life because, like I said, he's in serious condition," Dr Ofer Merrin told The Times Of Israel.

Some witnesses were treated for shock, while others were enraged by the violence and chanted "death penalty for terrorists".

The attack follows a series of protests around the Middle East in the wake of President Trump's controversial decision to move the US embassy to Jerusalem.

The decision is a departure from a decades-old position by most countries that Jerusalem's fate would be decided in negotiations between the Israelis and Palestinians as part of a peace agreement.